Decide at what time you would like to wake up. So if you're trying to go to bed at 10, and get 8 hours of sleep, then set your alarm to 6 or 6.30AM (depends on how long it takes you to fall asleep). It's gonna suck for the first few days but eventually you'll be so tired that you'll start going to bed earlier, eventually reaching your goal. There might be more subtle methods, but this is what I do.
This only works if you can actually wake up with a low amount of sleep. I put one of those alarms on my phone where you have to solve maths problems to turn it off. All I've managed to do so far is train myself to do maths in my sleep...
I did the same thing. It got to the point where I had to set it to about 5 snoozes of 3 hard math problems then a final 5 problem set.
It worked for a few months, but eventually I began just hard powering down the phone and falling back asleep for hours.
Needless to say, I have never been successful at any job or school where I wasn't able to work afternoons or nights. I don't even bother applying for jobs that do a typical 9-5.
It has kind of set my life on a strange course.
And it's now almost 7am, I haven't slept, and I will probably end up staying up all day...
Surely this is primarily a question of willpower. Before you go to bed, commit to this action: when the alarm goes off, I will immediately get up. It quickly becomes habit.